*I got dried lemongrass from a health food market up the street and my lovely sister Bea was an incredible sous chef and chopped them up as if I had a mortar and pestle! Although it did make a mess.
If you can't find ground or dried lemongrass you can chop 1 T. fresh lemongrassn finely and boil them for 10 minutes in 1/2 cup water. Allow to steep, or soak, for 10 minutes, strain, and use the reserved liquid as the hot water for the sponge mix.

Gradually add the sugar and continue beating until dissolved. Add the yolks and lime zest and beat just to combine. Sift together flour and lemongrass and gently fold through the egg mixture followed by the water or lemongrass juice.

Spoon mixture into prepared pan and bake for 20-25 minutes or until golden and cake springs back when pressed gently. Leave in pan for 5-10 minutes before turning onto a wire rack to cool.

To make lime cream, place all ingredients in a bowl and beat with an electric mixer until thick and creamy.

Cut sponge cake in half and fill with the lime cream. Sprinkle top with powdered sugar.